Reservoir connectivity analysis determines whether reservoir fluids flow from one reservoir section to another reservoir section and where to drill a wellbore. Reservoir connectivity may be assessed by collecting and analyzing oil samples from a wellbore using Downhole Fluid Analysis (DFA), including optical spectroscopy to determine heavy end concentration at different depths in the wellbore and comparing to a Flory-Huggins-Zuo Equation of State (FHZ EOS) oils. This analysis relies on the interpretation of the optical absorption in the visible or near infrared region (referred to as “color”) and is related to the relative content of asphaltenes or colored resins in the oil. It is difficult, however, to quantify the asphaltene content in some oils. Some systems measure relative asphaltene content using color and heavy oil fluorescence, both of which are appropriate for oils with a high concentration of heavy ends. These methods may not be viable for oils with a low concentration of heavy ends, such as gas condensates.